MoveOn.org, a liberal political group, said Thursday it has launched a petition drive that calls on America Online Inc. to halt plans to launch a paid certified email service that would bypass spam filters and deliver messages directly to subscribers.

The online petition was emailed to all 3 million MoveOn.org members on Wednesday, Adam Green, spokesman for the political group's Civic Action unit, said. MoveOn.org members who subscribe to AOL, a division of Time Warner Inc, were sent the petition last week.

The group has gathered more than 200,000 signatures, Green said.

MoveOn.org plans to hold a news conference on Tuesday to unveil a number of organizations that have joined it in opposing AOL's pay-to-send system, Green said. Those groups include political organizations from the left and the right, nonprofits, businesses and Internet advocacy groups. Among the Internet entrepreneurs who have joined the petition drive is Craig Newmark, founder of the popular CraigsList online classifieds service, Green said.

MoveOn.org claims AOL's certified email program, which it plans to launch this quarter, would eventually lead to slower delivery and inferior service for charities, small businesses, civic organizations and individuals who can't afford to pay for sending bulk email.

In addition, offering guaranteed delivery only to paying email senders destroys the Internet as a neutral platform in which everyone is treated equally, a practice that has enabled Internet startups to compete with larger established firms, MoveOn.org said.

"The Internet only thrives if it's free to everybody, and everybody is equal on it," Green said. "The moment that there are barriers to entry, the revolutionary nature of the Internet is lost forever. Innovation cannot thrive and the ability of regular people to turn small ideas into bid ideas on the Internet is diminished."

AOL, which has 26 million subscribers, said MoveOn.org was wrong in saying that email services for nonpaying senders would degrade. The two organizations had met before the start of the petition drive, but failed to reach an agreement.

"We don't mind when organizations make philosophical and political arguments, as long as they have the correct facts," AOL spokesman Nicholas Graham said. "After having a conversation with them, it was pretty clear they weren't interested in providing their members with accurate information or the truth." In adding a certified email service, nothing would change for users of AOL's free service, Graham said. The benefit to paying customers, however, would be guaranteed delivery of their email and all its content to a person's inbox, provided that person agreed to receive the email.

Companies that send legitimate email today over AOL's network run the risk having the portal's spam filter strip the message of links, images and attachments. In addition, there's no guarantee the email won't end up in a junk box set aside for spam, Graham said.

Steve Ratzlaff, vice president of marketing for Greyware Automation Products Inc., a Plano, Texas, provider of Web and email tools for businesses, sided with AOL, saying MoveOn.org was giving an inaccurate depiction of AOL's upcoming service, and was using inflammatory rhetoric to attract Internet users.

"It's inaccurate in every respect," Ratzlaff said of MoveOn.org's position.

The AOL service, provided through Goodmail Systems Inc., would be valuable to large companies that often have their brands hijacked by phishers trying to lure people to bogus Web sites to steal passwords and user IDs. Phishers often disguise email as coming from such well-known companies as EBay Inc., PayPal and a variety of financial institutions.

"Grandma's knitting circle passing out their monthly newsletter isn't getting phished," Ratzlaff said.

Certified email services make it possible for well-known companies to send bulk emails that customers know are legitimate, Ratzlaff said.

AOL and Yahoo Inc. announced in January their plans for pay-to-send services. Mail certified by the Web portals would contain an icon viewable from a person's list of inbox messages. The icon would authenticate the sender.

AOL said it would launch the service within 60 days, while Yahoo said it would be available in the "coming months."

MoveOn.org targeted AOL because it was more committed to its plans, Green said. "Yahoo was a little bit more tentative."

AOL, in the organization's view, also has enormous clout in the email market.

"As goes AOL, so will go the entire industry," Green said. "That's why it's important for regular people who care about the Internet to strike back now against AOL's email tax."

In unveiling the service in January, AOL said it had signed up the American Red Cross, The New York Times Co. and the credit report company Experian.

The announcement, however, was criticized at the time by some analysts, who argued that AOL and Yahoo should focus on making their spam filters better to avoid blocking legitimate email, rather than offering bypass routes for paying customers.